Self-expanding mandrel for pile casings



March 15, 1960 J. 5. MOKEE SELF-EXPANDING MANDREL FOR PILE CASINGS 4 Sheets-Sheet 1 Filed Nov. 5, 195

IN V EN TOR.

' March 15, 1960 J. 5. MOKEYE SELF-EXPANDING MANDREL FOR PILE CASINGS 4 Sheets-Sheet 2 Filed NOV. 5, 1956 INVENTOR.

March 15, 1960 J. s. McKEE 2,928,252

SELF-EXPANDING MANDREL FOR PILE CASINGS Filed Nov. 5, 1956 4 Sheet s-Sheet 3 March 15, 1960 J. 5. MCKEE 2,928,252

SELF-EXPANDING MANDREL FOR PILE CASINGS Filed Ndv. 5, 1956 4 Sheets-Sheet 4 l ww "with a and against whichall four segments ,will bear after the United States Patent:

For various types of construction it is desirable to have piles extending down into the earth to provide sufficiently dependable support for the structure to be built.

7 One preferred form of pile comprises a relatively thin steel shell filled with concrete. Both for economy and for best results, it is preferred that these steel shells be driven into the ground. This has been accomplished pile driving operation. A driving head suitable for direct co-operation with the pile driver, and also provided with means for withdrawing the mandrel, will be provided at the top of the mandrel, whether of one or more units.

for some years by placing in the steel shell an expanding mandrel which made possible the driving of the relatively weak steel'shell into the ground by operation of a pile driver on the top of the combined'assembly of shell and mandrel. I a According to the present invention, a greatly simplified expanding mandrelforthis purpose is provided. The simplification is achieved chiefly by making the mandrel self-expanding in the sense that the main longitudinal stringers of the mandrel which must be thrust apart for gripping the inside of the pile casing or shell, are also the main operating members by which the expam :sion is produced. Heretofore, the'expansion has involved some sort' of a core which thrusts apart the 'main segments or longitudinal stringers, but such core-is not required by the present invention. h

According to the present invention, the mandrel includes four sturdy longitudinally extending segments much as before. When they are inserted into the pile shell, only two of the four rest on the bottom of the Additional objects and advantages of the invention will be apparent from the following description and from the drawings.

Designation of figures Fig. 1 is a somewhat diagrammatic view showing an expanded mandrel in a shell being driven into the ground.

Figs. 2 and 3 are upper and lower portions of the expanded mandrel unit in Fig. 1, with portions broken away. a

, Figs. 4 and 5 are horizontal sectional-views taken approximately at 44 and 5-5 of Fig. 2.

Fig. 6 .is a top view of one of the mandrel segments.

Fig. 7 is a horizontal sectional view of one of the mandrel segments, being taken through a hand hole.

Fig. 8 is a view showing the relationship of the .expanded mandrel, the driving head and the lifting ring.

Fig. 9 is an exploded view showing the upper portions of three of the four segments, the face plates being partly omitted.

Fig. 10 is a somewhat diagrammatic view partly in ver- 1 tical cross-section, and with portions omitted, showing a Shell initially. They may be called passive segments.

'The other two, called active segments, are somewhat raised in position. Between the passive segments and the active segments, wedges are provided, so'that as the active segments are driven down to a seated position,

all four segments are wedged apart to press themselves firmly against the inside surfaces of the pile shell, forming 'a firm driving unit. To remove the mandrel the two active segments are initially raised thereby releasing the wedges from one another so. that the mandrel foursegments draw together. The collapsing action may be ensured by means for positively drawing the segments toward one anotherasthe first two segments are raised. This may be accomplished by camming means secured to the respective segments," in which event the same means may'serve the function of maintaining the four stringers approximately equally spaced at all times.

, It is not necessary that the segments be unitary for the full length -of the pileshell. Mandrel units including four segments each may be made up in convenient lengths and it is quite easy to combine theminto a chain. After one unit has been moved into a. shell, and perhaps after it is driven, its. two active segments may be secured to the two active segments of another unit so that the two may collapse by having its multi-unit mandrel with the active segments of the upper units connected to the driving head, so that the entire mandrel can be lifted by the lifting ring. I

Fig. 11 is a similar view showing the parts after the upper mandrel has been expanded and the shells welded together. V 1 1 Intent clause Although the law requires a full and exact description of at least one form of the invention, suchas that which follows,it is, of course, the purpose of a patent to cover each new inventive concept therein no matter how it may later be'disguised by variations in form or additions of further improvements; and the appended claims are intended to accomplish this purpose by particularly pointing out the parts, improvements, or combinations in which -the inventive concepts are found.

General description mandrel and withdrawing it from the shell. The shell will then be filled with concrete to provide a cast-inplace concrete pile. The present invention is concerned especially with the construction of the expanding mandrel12.

The mandrel is made up of four segments 16, two of which may :be more specifically designated as 16A and the other two as 16P. The two segments 16A may be called active segments and the two segments 16P may pnits would then function as one mandrel. There may I be sorne difierences between thesuccessive units. The

first' it will normally be provided at its entering end base plate'carrie'd by the'two passive segments,

active segmentshavebeen'driven "home; and during the be called passive segments. During expansion and col lapsing, the active segments move up and down relative to the passive segments. As seen perhaps best in Fig. 2, wedges'17A are provided on the active segments 16A,

and co-operating wedges17P are provided on the passive segments 16P. As the active segments are driven down from a position above that shown in Fig. 2, the interaction of the wedges 17A and 17P 'spre'adsthe segments apart. Fig. 2 shows only one set of wedges, but aswill be seen from Fig. 9, each active segment-16A Patented Mar. 15, 1960 has wedge means 17A on one face for engaging one of the segments 16F and another Wedge means 17A on its other face for engaging the other of the passive segments 16F. The other of the active segments likewise has wedges engaging wedges on both of the passive segments. The various sets of wedges are located at a suflicient number of points along the length of the segments so that the segments will not flex unduly between wedges, and will engage the shell along its full length.

When the active segments are drawn upwardly so that the wedges no longer hold the segments spread apart, the segments may be drawn together in a suitable manner. Although springs may be sufficient, the present preference is for providing cam plates 18 on the active segments riding in slots 19 on the passive segments. One reason these cam plates are preferred at present is that they also serve the additional purposes of raising the passive segments after sufiicient lost motion to permit collapsing, and maintaining proper alignment or relative disposition of the four segments as they expand and contract, keeping them equally spaced. Without some such guide, the two active segments might move closer together or further apart than the spacing of the passive segments and possibly distort the shell to an oval crosssection. Alignment guides which do not serve as collapsing cams could be used for this latter function, and other limits of relative movement could be used.

Structure of segments Each segment may desirably comprise mainly a steel angle bar 21 extending its full length and a shell face plate 22 also extending the full length. Although these may be welded together along'their full length, that does not appear to be necessary. They should be welded together at frequent intervals, however. Before they are welded together, a series of gusset plates 23 may be welded Within the angle bars, serving both to reinforce the angle bars and to provide a support for the central portion of the face plate 22. At the present time, however, it is believed that these need only be provided in the vicinity of the wedges, where they will serve the additional purpose of transmitting the wedging thrust to the face plate 22 and safeguarding against distortionof the angle bars 21 by the wedging pressure. The segments could also be cast.

Wherever necessary for access in assembly or for purposes described below, hand holes 26 may be provided as shown in Fig. 8. Cover plates may be fitted in these holes to rest against'suitable'internal flanges, if conditions 7 are such that the shell may othewise be pressed into the holes.

At the upper ends of the two active segments 16A, holes may be provided for the passage of pin 27. The hole 28 in the face plate 22 may be relatively large, but the .hole 29 through the angle bar 21 preferably fits the pin 27 more closely, for load bearing purposes. As a matter of fact, it is desirable to reinforce the angle bar 21 in the vicinity of each of the holes 29, as by welding plates 31 to them, and perhaps plates 32 on the inside. Such reinforcing at the upper and lower ends ofall of the angle bars 21 may be desirable, to help transmitthe pile driver blows.

The slots 19 may be formed by welding two short spacer plates 33 to .one face of the angle bar 21 and welding a longer plate 34 to the two spacer plates and bridging between them as shownin Fig. 9.

AlthoughFigs. 4 and 5 and some other figures indicate numerous bolts for holding the parts together, it is generally preferred that weldingbeused. Adjustment of wedges:originally,;or after-wear, may bedone by inser- .tion.,of.shims (if not welded),, resurfacing the wearing faces" or addition of, new wearing surfaces. Sometimes it. canbe'done by-adding'shim plates to the top of the active segments 16A and to the bottom of passive segmen'ts 16F.

' After-ohenshell .1 1 has Base plate Before driving the shell 11, it will be provided with a boot 36 secured and sealed to the shell, as by welding. To safeguard against punching through this boot 36, and to ensure distributed bearing thereon, the bottom of the mandrel is provided with a base plate 37 as seen in Fig. 3. It is necessary that this base plate be carried in a manner which does not interfere with the expanding and contracting action of the segments. To this end, the base plate may be secured in a manner illustrated in Fig. 3. A bolt 38 may extend through the base plate to a gusset plate 39 substantially above the base plate. The end plate 41 of the segment 16? is slotted to permit the segment 16F to move inwardly and outwardly with re spect to the bolt 38 and the base plate 37. Any gusset plates 43 between the gusset plate 39 and the end plate 41 are similarly slotted. Only two bolts 38 are provided, one extending into and being secured to each of the passive segments 16F. Thus the active segments 16A are left free to move vertically. The top of each segment is also provided with an end plate 41.

Driving head The driving head '13 may be in the form ,shown in Fig. 8. The upper portion is shaped for conventionally engaging the pile driver, and the lower portionis adapted to surround the mandrel and bear against its upper end. Pin 27 extends through its skirt and thus holds the mandrel, or at least the two active segments 16A within the skirt. After the two active segments have been driven to thesame level as the two passive segments, the body of the driving head 13 will rest on all four segments. At present it is preferred that the entire assembly be supported and held in proper relationship with the pile driver mechanism, represented diagrammatically at 45, ,Fig. 11, by alifting ring 14 which may be provided with suitableears-47 to which a cable may be secured for binding the ring 14 to the pile driver structure. It will be observedthat the head 13 can rotate within the ring 14, and therefore a spirally corrugated shell is free to screw itself intothe ground as it is driven.

Cleats gripping surfaces may be applied to the mandrel Segments when necessary with smooth shells. For some conditions cleats or gripping surfaces may also be desirable on the 7 active segments 16A,,although the care required inspacing and forming them to clear the internal ribs in the shells as the segments move up or down for collapsing .or expanding themandrel, indicatesv omitting these unless found necessary.

Chain of mandrel-units When it is desired to drive .a pile deeper than the length of one mandrel unit, this can be accomplished by providing a chain of mandrel units as seen in Fig. 10. Acpnnecting link 51 is used folconnectingtheactive segments of the two units. Thus a pin 52 extends throu'ghthe link 51 and into the active. segments 16A of the HD116 units of the chain of mandrel units, and a second pin 52px tends through the link 51 and into the segments-16A of the lower unit. Preferably the lower or thesepins '52 extends through alostmotion slot 4 in the'whichis long enough for the following operation: a

' n iltive ll lintO- t flg fb ll l until it is nearly ,flush'. there ith,ltli e pinf27, loffFigIf8 can .be withdrawnand .the driving head 13 and'ring 14 canbe lifted away and secured toanother mandrel unit.

7 After th an s un hasbcr r a d g q-a 9924 5. shell and the latter held thereon temporarily in a suitable manner (as by rope 55), this shell and mandrel can be lowered to the'position shown in Fig. with the two passive segments of the upper unit resting on the passive segments of the lower unit. The link 51 will have been secured to the upper unit by upper pin 52 before the upper unit is quite lowered to this position. At this time the. lower pin 52 can he slipped in place. The ring 14 may now be raised to draw the lower active segments 16A upwardly enough to allow at least partial collapsing of the lower mandrel unit. Thereupon the upper shell may be, loosened and lowered to slide over the lower mandrel unit until it is in contactwith the lower shell 11. The two sections of shell may then be joined together, and sealed if necessary, in a suitable manner, as by welding, screwing together or applying a sleeve or sleeves welded or otherwise sealed to them. Now the upper mandrel unit may be lowered until the passive segments of it again rest on the passive segments of the lower mandrel unit. At this time, the link 51 will probably drop to a point where it is no longer supporting the pin 52. .As the upper active segments 16A are driven downwardly, they will come into engagement with the lower active segments 16A and drive them downwardly also. When the lower active segments 16A have thus been driven down to the level of the passive segments, the upper active segments 16A will also be driven to the level of the upper passive segments, and both mandrel 6 opposite pain-of segments facing upwardly, and th wedges being so positioned that as the active segments are driven down with respect to the passive segments tothe same level, the mandrel unit will be expanded with the wedges .in engagement, the active pair of segments being shiftable upwardly from the level of the other segments and as. they are so shifted, the mandrel unit being collapsible to lie;within a smaller diameter than ,that which it occupies when expanded.

2. An expanding mandrel unit according to claim l, including a base plate carried entirely by the second pair of segments, with freedom of the second pair of segments to shift inwardly and outwardly, and freedom of the active segments to shift upwardly and downwardly.

3. An expanding mandrel comprising two units one above the other, each a mandrel as defined in claim 1, with, the activeysegments of one unit secured to the active segments of the other unit.

4. An expanding mandrel in accordance with claim 3, in which the segments secured together are secured with a lost motion connection allowing the upper unit to rest with all of its segments on the segments of the lower unit and alternatively to be collapsed without collapsing the lower unit.

5. An expanding mandrel unit in accordance with claim 1, including cam means co-operating between the active segments and the other segments to collapse the mandrel as the active segments are raised,

units will be properly expanded to permit further driving of the now combined shell until it has been driven enough further for the upper shell also to be at ground level. If greater depth is required, the same process may be repeated with a third mandrel unit, and a third shell.

The pins 52 may be kept centered, or retained within the mandrels in any suitable manner, as by a spring latch engaging them, or a draw bolt blocking their'removal.

In some instances, it may be preferred to make a two unit mandrel without the lost motion provided by slot 54. Either the active segments may be coupled snugly by a link such as 54, but shorter, or each of the active (or each of all four) upper segments can be rigidly secured to the corresponding lower segment. For this'purpose, holes 56 may be provided in all end plates 41, so they may easily be bolted together. Where the hole is elongated to permit movement of bolt 38, the securing bolt may be of corresponding cross-section.

If a pile is desired that is larger in its upper portions than below, this can be accomplished by driving the used, but would be of utility also if a separate stringer In that event a the cores would be the active stringers and would-be linked as described above with respect to the active in the form of a wedging core were used.

stringers heretofore called segments. The remaining or passive stringers or segments would be treated as described for the passive segmentsabove.

I claim: x

1. An expanding mandrel unit for driving pile casings including four sturdy longitudinal segments each adapted 'to transmit driving load, and to back up the casing, arranged in a group with a face of each exposed peripherally, with wedge means secured to-each segment and engaging the companion wedge means on the adjacent segments, the wedges on an active opposite pair of said segments facing downwardly and the wedges on the second A suitable coupling.

6. An expanding mandrel unit in accordance with claim 1, including cam means co-operating between the active segments'and the other segments to collapse the mandrel as the active segments are raised and to maintain alignment of the segments. I

7. An expanding mandrel unit in accordance with claim 1, including cam means co-operating between the active segments and the other segments to collapse the mandrel as the active segments are raised and to raise the other segments as upward movement of the active segments is continued beyond the amount required for collapsing.

S. An expanding mandrel unit in accordance with claim 1, including means to maintain alignment of the segments.

9. An expanding mandrel unit in accordance with claim 1, including means to raise the other segments as upward movements of the active segments is continued beyond the amount required for collapsing.

10. An expanding mandrel unit for driving pile casings including a plurality of. sturdy longitudinal segments each adapted totransmit driving load, and to back up the casing, arranged in a group with a face of each exposed peripherally, with wedge means secured to each segment and engaging the companion wedge means on an adjacent segment, the wedges on at least one active segment of said segments facing downwardly andthe wedges on the segment adjacent to the active segment or segments facing upwardly, and the wedges being so positioned that as the active segments are driven down with respect to the passive segments to the same level, the mandrel unit will be' expanded with the wedges in engagement, the active segment being shiftable upwardly from the level of the other segments and as they are so shifted, the mandrel unit being collapsible to lie within a smaller cross-section than that which it occupies when expanded.

11. A chain of expanding mandrel units, each having a plurality of passive stringers and an active stringer for allowing them to move toward one another to collapse the unit when the active stringer is raised; means. separably linking the active stringers together and when 'connecting them providing lost motion so that the upper stringer can be raised to-collapse its unit, raised further to raise the lower active stringer to collapse the lower unit, and driven down with the upper passive stringers resting on the lower passive stringers, to expand 'both units; and means to'raise the'passive stringers by support from the active stringers after the units have collapsed.

12. A chain of expanding mandrel units, each having a plurality of passive stringers and an active stringer movable longitudinally between them and having an exposed head for being driven, and having a fitting for being raised by a cable,v said stringers having spreading means associated with them for spreading the passive stringers apart when the active stringer is driven downwardly and' for allowing them to move toward one another to collapse the unit when the active stringer is raised; meanslinking the active stringers together and when connecting'them providing lost motion so that the upper stringer can be raised to collapse its unit, raised further to raise he aws: active s n r col ap e he lower unit; and driven; down, with the upper passive stringers resting onfthelqwer passive stringers, to ex? 777,351 Raymond Dec. 13, 1904 1,3 8 D aly -+--.--.--v-v i 3, 1932 2 437,( )43 Riem 1hnider et al. Mar. 2, 1948 EQREIGN PATENTS 

